diff --git a/crates/tek_core/src/engine.rs b/crates/tek_core/src/engine.rs
index d5fb7bff..0958fbef 100644
--- a/crates/tek_core/src/engine.rs
+++ b/crates/tek_core/src/engine.rs
@@ -6,7 +6,7 @@ pub trait App<T: Engine> {
 }
 
 /// Platform backend.
-pub trait Engine: Sized {
+pub trait Engine: Send + Sync + Sized {
     fn setup (&mut self) -> Usually<()> { Ok(()) }
     fn exited (&self) -> bool;
     fn teardown (&mut self) -> Usually<()> { Ok(()) }
diff --git a/crates/tek_core/src/lib.rs b/crates/tek_core/src/lib.rs
index 0ba950a9..40967bd3 100644
--- a/crates/tek_core/src/lib.rs
+++ b/crates/tek_core/src/lib.rs
@@ -9,6 +9,7 @@ pub use once_cell::sync::Lazy;
 pub use std::sync::atomic::{Ordering, AtomicBool};
 pub use std::rc::Rc;
 pub use std::cell::RefCell;
+pub use std::marker::PhantomData;
 pub(crate) use std::error::Error;
 pub(crate) use std::io::{stdout};
 pub(crate) use std::thread::{spawn, JoinHandle};
diff --git a/crates/tek_mixer/src/mixer.rs b/crates/tek_mixer/src/mixer.rs
index a04a4309..a5a54fa5 100644
--- a/crates/tek_mixer/src/mixer.rs
+++ b/crates/tek_mixer/src/mixer.rs
@@ -30,12 +30,13 @@ impl<E: Engine> Process for Mixer<E> {
         Control::Continue
     }
 }
-impl Render<Tui> for Mixer<Tui> {
-    fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
+impl Content for Mixer<Tui> {
+    type Engine = Tui;
+    fn content (&self) -> impl Widget<Engine = Tui> {
         let mut tracks = Split::right();
         for channel in self.tracks.iter() {
             tracks = tracks.add_ref(channel)
         }
-        tracks.render(to)
+        tracks
     }
 }
diff --git a/crates/tek_mixer/src/track_view.rs b/crates/tek_mixer/src/track_view.rs
index eb26cc8b..efb7838f 100644
--- a/crates/tek_mixer/src/track_view.rs
+++ b/crates/tek_mixer/src/track_view.rs
@@ -1,13 +1,9 @@
 use crate::*;
 use tek_core::Direction;
 
-impl Layout<Tui> for Track<Tui> {
-    fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
-        todo!()
-    }
-}
-impl Render<Tui> for Track<Tui> {
-    fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
+impl Content for Track<Tui> {
+    type Engine = Tui;
+    fn content (&self) -> impl Widget<Engine = Tui> {
         TrackView {
             chain:     Some(&self),
             direction: tek_core::Direction::Right,
@@ -26,7 +22,7 @@ impl Render<Tui> for Track<Tui> {
             //pub output_ports:      Vec<Port<AudioOut>>,
             //pub post_fader_meter:  f64,
             //pub route:             String,
-        }.render(to)
+        }
     }
 }
 pub struct TrackView<'a, E: Engine> {
@@ -35,7 +31,11 @@ pub struct TrackView<'a, E: Engine> {
     pub focused:   bool,
     pub entered:   bool,
 }
-impl<'a> Render<Tui> for TrackView<'a, Tui> {
+impl<'a> Widget for TrackView<'a, Tui> {
+    type Engine = Tui;
+    fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
+        todo!()
+    }
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         todo!();
         //let mut area = to.area();
diff --git a/crates/tek_sequencer/src/arranger.rs b/crates/tek_sequencer/src/arranger.rs
index 8fcdeee2..f2f74642 100644
--- a/crates/tek_sequencer/src/arranger.rs
+++ b/crates/tek_sequencer/src/arranger.rs
@@ -6,7 +6,7 @@ pub struct Arranger<E: Engine> {
     /// Name of arranger
     pub name:     Arc<RwLock<String>>,
     /// Collection of tracks.
-    pub tracks:   Vec<Sequencer>,
+    pub tracks:   Vec<Sequencer<E>>,
     /// Collection of scenes.
     pub scenes:   Vec<Scene>,
     /// Currently selected element.
@@ -45,12 +45,12 @@ impl<E: Engine> Arranger<E> {
             _ => {}
         }
     }
-    pub fn sequencer (&self) -> Option<&Sequencer> {
+    pub fn sequencer (&self) -> Option<&Sequencer<E>> {
         self.selected.track()
             .map(|track|self.tracks.get(track))
             .flatten()
     }
-    pub fn sequencer_mut (&mut self) -> Option<&mut Sequencer> {
+    pub fn sequencer_mut (&mut self) -> Option<&mut Sequencer<E>> {
         self.selected.track()
             .map(|track|self.tracks.get_mut(track))
             .flatten()
@@ -99,13 +99,11 @@ impl ArrangerViewMode {
         }
     }
 }
-impl Layout<Tui> for Arranger<Tui> {
+impl Widget for Arranger<Tui> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-/// Render arranger to terminal
-impl Render<Tui> for Arranger<Tui> {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let area = (|to|match self.mode {
             ArrangerViewMode::Horizontal =>
diff --git a/crates/tek_sequencer/src/arranger_rename.rs b/crates/tek_sequencer/src/arranger_rename.rs
index 62f82aa6..ce547f1d 100644
--- a/crates/tek_sequencer/src/arranger_rename.rs
+++ b/crates/tek_sequencer/src/arranger_rename.rs
@@ -13,16 +13,18 @@ impl Arranger<Tui> {
     }
 }
 /// Appears on first run (i.e. if state dir is missing).
-pub struct ArrangerRenameModal {
+pub struct ArrangerRenameModal<E: Engine> {
+    _engine: std::marker::PhantomData<E>,
     done:   bool,
     target: ArrangerFocus,
     value:  String,
     result: Arc<RwLock<String>>,
     cursor: usize
 }
-impl ArrangerRenameModal {
+impl<E: Engine> ArrangerRenameModal<E> {
     pub fn new (target: ArrangerFocus, value: &Arc<RwLock<String>>) -> Self {
         Self {
+            _engine: Default::default(),
             done: false,
             target,
             value:  value.read().unwrap().clone(),
@@ -31,7 +33,11 @@ impl ArrangerRenameModal {
         }
     }
 }
-impl Render<Tui> for ArrangerRenameModal {
+impl Widget for ArrangerRenameModal<Tui> {
+    type Engine = Tui;
+    fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
+        todo!()
+    }
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let area = to.area();
         let y = area.y() + area.h() / 2;
@@ -53,7 +59,7 @@ impl Render<Tui> for ArrangerRenameModal {
         Ok(Some(area))
     }
 }
-impl Handle<Tui> for ArrangerRenameModal {
+impl Handle<Tui> for ArrangerRenameModal<Tui> {
     fn handle (&mut self, from: &Tui) -> Perhaps<bool> {
         match from.event() {
             TuiEvent::Input(Event::Key(k)) => {
@@ -91,7 +97,7 @@ impl Handle<Tui> for ArrangerRenameModal {
         }
     }
 }
-impl Exit for ArrangerRenameModal {
+impl<E: Engine + Send> Exit for ArrangerRenameModal<E> {
     fn exited (&self) -> bool {
         self.done
     }
@@ -99,8 +105,3 @@ impl Exit for ArrangerRenameModal {
         self.done = true
     }
 }
-impl Layout<Tui> for ArrangerRenameModal {
-    fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
-        todo!()
-    }
-}
diff --git a/crates/tek_sequencer/src/arranger_track.rs b/crates/tek_sequencer/src/arranger_track.rs
index 267009b2..74404c54 100644
--- a/crates/tek_sequencer/src/arranger_track.rs
+++ b/crates/tek_sequencer/src/arranger_track.rs
@@ -4,10 +4,10 @@ use super::Arranger;
 
 /// Track management methods
 impl<E: Engine> Arranger<E> {
-    pub fn track (&self) -> Option<&Sequencer> {
+    pub fn track (&self) -> Option<&Sequencer<E>> {
         self.selected.track().map(|t|self.tracks.get(t)).flatten()
     }
-    pub fn track_mut (&mut self) -> Option<&mut Sequencer> {
+    pub fn track_mut (&mut self) -> Option<&mut Sequencer<E>> {
         self.selected.track().map(|t|self.tracks.get_mut(t)).flatten()
     }
     pub fn track_next (&mut self) {
@@ -16,7 +16,7 @@ impl<E: Engine> Arranger<E> {
     pub fn track_prev (&mut self) {
         self.selected.track_prev()
     }
-    pub fn track_add (&mut self, name: Option<&str>) -> Usually<&mut Sequencer> {
+    pub fn track_add (&mut self, name: Option<&str>) -> Usually<&mut Sequencer<E>> {
         self.tracks.push(name.map_or_else(
             || Sequencer::new(&self.track_default_name()),
             |name| Sequencer::new(name),
@@ -32,13 +32,13 @@ impl<E: Engine> Arranger<E> {
     }
 }
 
-pub fn track_name_max_len (tracks: &[Sequencer]) -> usize {
+pub fn track_name_max_len <E: Engine> (tracks: &[Sequencer<E>]) -> usize {
     tracks.iter()
         .map(|s|s.name.read().unwrap().len())
         .fold(0, usize::max)
 }
 
-pub fn track_clip_name_lengths (tracks: &[Sequencer]) -> Vec<(usize, usize)> {
+pub fn track_clip_name_lengths <E: Engine> (tracks: &[Sequencer<E>]) -> Vec<(usize, usize)> {
     let mut total = 0;
     let mut lengths: Vec<(usize, usize)> = tracks.iter().map(|track|{
         let len = 4 + track.phrases
diff --git a/crates/tek_sequencer/src/arranger_view_h.rs b/crates/tek_sequencer/src/arranger_view_h.rs
index 4b91ee80..fdf47da2 100644
--- a/crates/tek_sequencer/src/arranger_view_h.rs
+++ b/crates/tek_sequencer/src/arranger_view_h.rs
@@ -17,15 +17,13 @@ pub fn draw (state: &Arranger<Tui>, to: &mut Tui) -> Perhaps<[u16;4]> {
     ]).render(to.with_rect(area))
 }
 
-struct TrackNameColumn<'a>(&'a [Sequencer], ArrangerFocus);
+struct TrackNameColumn<'a>(&'a [Sequencer<Tui>], ArrangerFocus);
 
-impl<'a> Layout<Tui> for TrackNameColumn<'a> {
+impl<'a> Widget for TrackNameColumn<'a> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for TrackNameColumn<'a> {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         todo!();
         //let Self(tracks, selected) = self;
@@ -51,15 +49,13 @@ impl<'a> Render<Tui> for TrackNameColumn<'a> {
     }
 }
 
-struct TrackMonitorColumn<'a>(&'a [Sequencer]);
+struct TrackMonitorColumn<'a>(&'a [Sequencer<Tui>]);
 
-impl<'a> Layout<Tui> for TrackMonitorColumn<'a> {
+impl<'a> Widget for TrackMonitorColumn<'a> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for TrackMonitorColumn<'a> {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         todo!();
         //let Self(tracks) = self;
@@ -86,15 +82,13 @@ impl<'a> Render<Tui> for TrackMonitorColumn<'a> {
     }
 }
 
-struct TrackRecordColumn<'a>(&'a [Sequencer]);
+struct TrackRecordColumn<'a>(&'a [Sequencer<Tui>]);
 
-impl<'a> Layout<Tui> for TrackRecordColumn<'a> {
+impl<'a> Widget for TrackRecordColumn<'a> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for TrackRecordColumn<'a> {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         todo!();
         //let Self(tracks) = self;
@@ -121,15 +115,13 @@ impl<'a> Render<Tui> for TrackRecordColumn<'a> {
     }
 }
 
-struct TrackOverdubColumn<'a>(&'a [Sequencer]);
+struct TrackOverdubColumn<'a>(&'a [Sequencer<Tui>]);
 
-impl<'a> Layout<Tui> for TrackOverdubColumn<'a> {
+impl<'a> Widget for TrackOverdubColumn<'a> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for TrackOverdubColumn<'a> {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         todo!();
         //let Self(tracks) = self;
@@ -159,15 +151,13 @@ impl<'a> Render<Tui> for TrackOverdubColumn<'a> {
     }
 }
 
-struct TrackEraseColumn<'a>(&'a [Sequencer]);
+struct TrackEraseColumn<'a>(&'a [Sequencer<Tui>]);
 
-impl<'a> Layout<Tui> for TrackEraseColumn<'a> {
+impl<'a> Widget for TrackEraseColumn<'a> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for TrackEraseColumn<'a> {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         todo!();
         //let Self(tracks) = self;
@@ -192,15 +182,13 @@ impl<'a> Render<Tui> for TrackEraseColumn<'a> {
     }
 }
 
-struct TrackGainColumn<'a>(&'a [Sequencer]);
+struct TrackGainColumn<'a>(&'a [Sequencer<Tui>]);
 
-impl<'a> Layout<Tui> for TrackGainColumn<'a> {
+impl<'a> Widget for TrackGainColumn<'a> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for TrackGainColumn<'a> {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         todo!();
         //let Self(tracks) = self;
@@ -225,15 +213,13 @@ impl<'a> Render<Tui> for TrackGainColumn<'a> {
     }
 }
 
-struct TrackScenesColumn<'a>(&'a [Sequencer], &'a [Scene], ArrangerFocus);
+struct TrackScenesColumn<'a>(&'a [Sequencer<Tui>], &'a [Scene], ArrangerFocus);
 
-impl<'a> Layout<Tui> for TrackScenesColumn<'a> {
+impl<'a> Widget for TrackScenesColumn<'a> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for TrackScenesColumn<'a> {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let Self(tracks, scenes, selected) = self;
         let area = to.area();
diff --git a/crates/tek_sequencer/src/arranger_view_v.rs b/crates/tek_sequencer/src/arranger_view_v.rs
index 2a969b99..7921f0d4 100644
--- a/crates/tek_sequencer/src/arranger_view_v.rs
+++ b/crates/tek_sequencer/src/arranger_view_v.rs
@@ -51,13 +51,11 @@ pub fn draw <'a, 'b> (
 
 struct ColumnSeparators<'a>(u16, &'a [(usize, usize)]);
 
-impl<'a> Layout<Tui> for ColumnSeparators<'a> {
+impl<'a> Widget for ColumnSeparators<'a> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for ColumnSeparators<'a> {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let area = to.area();
         let Self(offset, cols) = self;
@@ -74,13 +72,11 @@ impl<'a> Render<Tui> for ColumnSeparators<'a> {
 
 struct RowSeparators<'a>(&'a [(usize, usize)]);
 
-impl<'a> Layout<Tui> for RowSeparators<'a> {
+impl<'a> Widget for RowSeparators<'a> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for RowSeparators<'a> {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let area = to.area();
         let Self(rows) = self;
@@ -103,13 +99,11 @@ struct CursorFocus<'a>(
     ArrangerFocus, u16, &'a [(usize, usize)], &'a [(usize, usize)]
 );
 
-impl<'a> Layout<Tui> for CursorFocus<'a> {
+impl<'a> Widget for CursorFocus<'a> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for CursorFocus<'a> {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let area = to.area();
         let Self(selected, offset, cols, rows) = *self;
@@ -173,15 +167,13 @@ impl<'a> Render<Tui> for CursorFocus<'a> {
     }
 }
 
-struct TracksHeader<'a>(u16, &'a[(usize, usize)], &'a [Sequencer]);
+struct TracksHeader<'a>(u16, &'a[(usize, usize)], &'a [Sequencer<Tui>]);
 
-impl<'a> Layout<Tui> for TracksHeader<'a> {
+impl<'a> Widget for TracksHeader<'a> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for TracksHeader<'a> {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let area = to.area();
         let Self(offset, track_cols, tracks) = *self;
@@ -199,15 +191,13 @@ impl<'a> Render<Tui> for TracksHeader<'a> {
     }
 }
 
-struct SceneRows<'a>(u16, &'a[(usize, usize)], &'a[(usize, usize)], &'a[Sequencer], &'a[Scene]);
+struct SceneRows<'a>(u16, &'a[(usize, usize)], &'a[(usize, usize)], &'a[Sequencer<Tui>], &'a[Scene]);
 
-impl<'a> Layout<Tui> for SceneRows<'a> {
+impl<'a> Widget for SceneRows<'a> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for SceneRows<'a> {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let area = to.area();
         let Self(offset, track_cols, scene_rows, tracks, scenes) = *self;
@@ -234,15 +224,13 @@ impl<'a> Render<Tui> for SceneRows<'a> {
     }
 }
 
-struct SceneRow<'a>(&'a[Sequencer], &'a Scene, &'a[(usize, usize)], u16);
+struct SceneRow<'a>(&'a[Sequencer<Tui>], &'a Scene, &'a[(usize, usize)], u16);
 
-impl<'a> Layout<Tui> for SceneRow<'a> {
+impl<'a> Widget for SceneRow<'a> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for SceneRow<'a> {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let area = to.area();
         let Self(tracks, scene, track_cols, offset) = self;
@@ -266,15 +254,13 @@ impl<'a> Render<Tui> for SceneRow<'a> {
     }
 }
 
-struct SceneClip<'a>(&'a Sequencer, usize);
+struct SceneClip<'a>(&'a Sequencer<Tui>, usize);
 
-impl<'a> Layout<Tui> for SceneClip<'a> {
+impl<'a> Widget for SceneClip<'a> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for SceneClip<'a> {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let area = to.area();
         let Self(track, clip) = self;
diff --git a/crates/tek_sequencer/src/scene.rs b/crates/tek_sequencer/src/scene.rs
index e8c6b76e..e762a77a 100644
--- a/crates/tek_sequencer/src/scene.rs
+++ b/crates/tek_sequencer/src/scene.rs
@@ -37,7 +37,7 @@ impl Scene {
         Self { name, clips, }
     }
     /// Returns the pulse length of the longest phrase in the scene
-    pub fn pulses (&self, tracks: &[Sequencer]) -> usize {
+    pub fn pulses <E: Engine> (&self, tracks: &[Sequencer<E>]) -> usize {
         self.clips.iter().enumerate()
             .filter_map(|(i, c)|c
                 .map(|c|tracks
@@ -50,7 +50,7 @@ impl Scene {
             .fold(0, |a, p|a.max(p.read().unwrap().length))
     }
     /// Returns true if all phrases in the scene are currently playing
-    pub fn is_playing (&self, tracks: &[Sequencer]) -> bool {
+    pub fn is_playing <E: Engine> (&self, tracks: &[Sequencer<E>]) -> bool {
         self.clips.iter().enumerate()
             .all(|(track_index, phrase_index)|match phrase_index {
                 Some(i) => tracks
@@ -68,7 +68,10 @@ pub fn scene_name_max_len (scenes: &[Scene]) -> usize {
         .fold(0, usize::max)
 }
 
-pub fn scene_ppqs (tracks: &[Sequencer], scenes: &[Scene]) -> Vec<(usize, usize)> {
+pub fn scene_ppqs <E: Engine> (
+    tracks: &[Sequencer<E>],
+    scenes: &[Scene]
+) -> Vec<(usize, usize)> {
     let mut total = 0;
     let mut scenes: Vec<(usize, usize)> = scenes.iter().map(|scene|{
         let pulses = scene.pulses(tracks).max(96);
diff --git a/crates/tek_sequencer/src/sequencer.rs b/crates/tek_sequencer/src/sequencer.rs
index bbb31ec2..a55f66dc 100644
--- a/crates/tek_sequencer/src/sequencer.rs
+++ b/crates/tek_sequencer/src/sequencer.rs
@@ -2,14 +2,14 @@ use crate::*;
 use tek_core::Direction;
 
 /// Phrase editor.
-pub struct Sequencer {
+pub struct Sequencer<E: Engine> {
     pub name:      Arc<RwLock<String>>,
     pub mode:      bool,
     pub focused:   bool,
     pub entered:   bool,
 
     pub phrase:    Option<Arc<RwLock<Phrase>>>,
-    pub transport: Option<Arc<RwLock<TransportToolbar>>>,
+    pub transport: Option<Arc<RwLock<TransportToolbar<E>>>>,
     pub buffer:    BigBuffer,
     pub keys:      Buffer,
     /// Highlight input keys
@@ -43,7 +43,7 @@ pub struct Sequencer {
     pub notes_out:  [bool;128],
 }
 
-impl Sequencer {
+impl<E: Engine> Sequencer<E> {
     pub fn new (name: &str) -> Self {
         Self {
             name:         Arc::new(RwLock::new(name.into())),
diff --git a/crates/tek_sequencer/src/sequencer_cli.rs b/crates/tek_sequencer/src/sequencer_cli.rs
index 71bf2283..719b8102 100644
--- a/crates/tek_sequencer/src/sequencer_cli.rs
+++ b/crates/tek_sequencer/src/sequencer_cli.rs
@@ -14,7 +14,7 @@ pub struct SequencerCli {
     #[arg(short, long)] transport: Option<bool>
 }
 
-impl Sequencer {
+impl Sequencer<Tui> {
     pub fn from_args () -> Self {
         let args = SequencerCli::parse();
         let mut seq = Self::new("");
diff --git a/crates/tek_sequencer/src/sequencer_handle.rs b/crates/tek_sequencer/src/sequencer_handle.rs
index ed6ae8a4..acd8328a 100644
--- a/crates/tek_sequencer/src/sequencer_handle.rs
+++ b/crates/tek_sequencer/src/sequencer_handle.rs
@@ -1,6 +1,6 @@
 use crate::*;
 
-impl Handle<Tui> for Sequencer {
+impl Handle<Tui> for Sequencer<Tui> {
     fn handle (&mut self, from: &Tui) -> Perhaps<bool> {
         match from.event() {
             // NONE, "seq_cursor_up",    "move cursor up", |sequencer: &mut Sequencer| {
diff --git a/crates/tek_sequencer/src/sequencer_view.rs b/crates/tek_sequencer/src/sequencer_view.rs
index 8fa93404..f1b0244a 100644
--- a/crates/tek_sequencer/src/sequencer_view.rs
+++ b/crates/tek_sequencer/src/sequencer_view.rs
@@ -1,11 +1,10 @@
 use crate::*;
 
-impl Layout<Tui> for Sequencer {
+impl Widget for Sequencer<Tui> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-impl<'a> Render<Tui> for Sequencer {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         self.horizontal_draw(to)?;
         if self.focused && self.entered {
@@ -15,7 +14,7 @@ impl<'a> Render<Tui> for Sequencer {
     }
 }
 
-impl Sequencer {
+impl<E: Engine> Sequencer<E> {
     /// Select which pattern to display. This pre-renders it to the buffer at full resolution.
     pub fn show (&mut self, phrase: Option<&Arc<RwLock<Phrase>>>) -> Usually<()> {
         self.phrase = phrase.map(Clone::clone);
diff --git a/crates/tek_sequencer/src/sequencer_view_h.rs b/crates/tek_sequencer/src/sequencer_view_h.rs
index 2126335c..d346eb45 100644
--- a/crates/tek_sequencer/src/sequencer_view_h.rs
+++ b/crates/tek_sequencer/src/sequencer_view_h.rs
@@ -1,6 +1,6 @@
 use crate::*;
 
-impl Sequencer {
+impl Sequencer<Tui> {
 
     const H_KEYS_OFFSET: usize = 5;
 
@@ -43,15 +43,13 @@ const STYLE_VALUE: Option<Style> = Some(Style {
     sub_modifier:    Modifier::DIM,
 });
 
-struct SequenceName<'a>(&'a Sequencer);
+struct SequenceName<'a>(&'a Sequencer<Tui>);
 
-impl<'a> Layout<Tui> for SequenceName<'a> {
+impl<'a> Widget for SequenceName<'a> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for SequenceName<'a> {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let [x, y, ..] = to.area();
         let frame = [x, y, 10, 4];
@@ -64,13 +62,11 @@ impl<'a> Render<Tui> for SequenceName<'a> {
 
 struct SequenceRange;
 
-impl Layout<Tui> for SequenceRange {
+impl Widget for SequenceRange {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for SequenceRange {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let [x, y, ..] = to.area();
         let frame = [x, y, 10, 6];
@@ -85,13 +81,11 @@ impl<'a> Render<Tui> for SequenceRange {
 
 struct SequenceLoopRange;
 
-impl Layout<Tui> for SequenceLoopRange {
+impl Widget for SequenceLoopRange {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for SequenceLoopRange {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let [x, y, ..] = to.area();
         let range = [x, y, 10, 7];
@@ -107,13 +101,11 @@ impl<'a> Render<Tui> for SequenceLoopRange {
 
 struct SequenceNoteRange;
 
-impl Layout<Tui> for SequenceNoteRange {
+impl Widget for SequenceNoteRange {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for SequenceNoteRange {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let [x, y, ..] = to.area();
         let range = [x, y, 10, 9];
@@ -129,15 +121,13 @@ impl<'a> Render<Tui> for SequenceNoteRange {
     }
 }
 
-struct SequenceKeys<'a>(&'a Sequencer);
+struct SequenceKeys<'a>(&'a Sequencer<Tui>);
 
-impl<'a> Layout<Tui> for SequenceKeys<'a> {
+impl<'a> Widget for SequenceKeys<'a> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for SequenceKeys<'a> {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let area = to.area();
         if area.h() < 2 {
@@ -154,15 +144,13 @@ impl<'a> Render<Tui> for SequenceKeys<'a> {
     }
 }
 
-struct SequenceNotes<'a>(&'a Sequencer);
+struct SequenceNotes<'a>(&'a Sequencer<Tui>);
 
-impl<'a> Layout<Tui> for SequenceNotes<'a> {
+impl<'a> Widget for SequenceNotes<'a> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for SequenceNotes<'a> {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let area = to.area();
         if area.h() < 2 {
@@ -189,15 +177,13 @@ impl<'a> Render<Tui> for SequenceNotes<'a> {
     }
 }
 
-struct SequenceCursor<'a>(&'a Sequencer);
+struct SequenceCursor<'a>(&'a Sequencer<Tui>);
 
-impl<'a> Layout<Tui> for SequenceCursor<'a> {
+impl<'a> Widget for SequenceCursor<'a> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for SequenceCursor<'a> {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let area = to.area();
         if let (Some(time), Some(note)) = (self.0.time_axis.point, self.0.note_axis.point) {
@@ -211,15 +197,13 @@ impl<'a> Render<Tui> for SequenceCursor<'a> {
     }
 }
 
-struct SequenceZoom<'a>(&'a Sequencer);
+struct SequenceZoom<'a>(&'a Sequencer<Tui>);
 
-impl<'a> Layout<Tui> for SequenceZoom<'a> {
+impl<'a> Widget for SequenceZoom<'a> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for SequenceZoom<'a> {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let area = to.area();
         let quant = ppq_to_name(self.0.time_axis.scale);
@@ -229,15 +213,13 @@ impl<'a> Render<Tui> for SequenceZoom<'a> {
     }
 }
 
-struct SequenceTimer<'a>(&'a Sequencer, Arc<RwLock<Phrase>>);
+struct SequenceTimer<'a>(&'a Sequencer<Tui>, Arc<RwLock<Phrase>>);
 
-impl<'a> Layout<Tui> for SequenceTimer<'a> {
+impl<'a> Widget for SequenceTimer<'a> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         todo!()
     }
-}
-
-impl<'a> Render<Tui> for SequenceTimer<'a> {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let area = to.area();
         let phrase = self.1.read().unwrap();
@@ -250,7 +232,7 @@ impl<'a> Render<Tui> for SequenceTimer<'a> {
         for x in x2..x3 {
             let step = (time0 + x2) * time_z;
             let next_step = (time0 + x2 + 1) * time_z;
-            let style = Sequencer::style_timer_step(now, step as usize, next_step as usize);
+            let style = Sequencer::<Tui>::style_timer_step(now, step as usize, next_step as usize);
             to.blit(&"-", x as u16, area.y(), Some(style))?;
         }
         return Ok(Some([area.x(), area.y(), area.w(), 1]))
diff --git a/crates/tek_sequencer/src/transport.rs b/crates/tek_sequencer/src/transport.rs
index 9f35602e..2bfa5da6 100644
--- a/crates/tek_sequencer/src/transport.rs
+++ b/crates/tek_sequencer/src/transport.rs
@@ -1,7 +1,7 @@
 use crate::*;
 
 /// Stores and displays time-related state.
-pub struct TransportToolbar {
+pub struct TransportToolbar<E: Engine> {
     /// Enable metronome?
     pub metronome: bool,
     /// Current sample rate, tempo, and PPQ.
@@ -16,13 +16,13 @@ pub struct TransportToolbar {
 
     pub focused:   bool,
     pub focus:     usize,
-    pub playing:   TransportPlayPauseButton,
-    pub bpm:       TransportBPM,
-    pub quant:     TransportQuantize,
-    pub sync:      TransportSync,
-    pub clock:     TransportClock,
+    pub playing:   TransportPlayPauseButton<E>,
+    pub bpm:       TransportBPM<E>,
+    pub quant:     TransportQuantize<E>,
+    pub sync:      TransportSync<E>,
+    pub clock:     TransportClock<E>,
 }
-impl TransportToolbar {
+impl<E: Engine> TransportToolbar<E> {
     pub fn standalone () -> Usually<Arc<RwLock<Self>>> {
         let mut transport = Self::new(None);
         transport.focused = true;
@@ -34,7 +34,7 @@ impl TransportToolbar {
         transport.write().unwrap().jack = Some(
             jack.activate(
                 &transport.clone(),
-                |state: &Arc<RwLock<TransportToolbar>>, client, scope| {
+                |state: &Arc<RwLock<TransportToolbar<E>>>, client, scope| {
                     state.write().unwrap().process(client, scope)
                 }
             )?
@@ -48,22 +48,27 @@ impl TransportToolbar {
             focus:   0,
 
             playing:   TransportPlayPauseButton {
+                _engine: Default::default(),
                 value:   Some(TransportState::Stopped),
                 focused: true
             },
             bpm:       TransportBPM {
+                _engine: Default::default(),
                 value:   timebase.bpm(),
                 focused: false
             },
             quant:     TransportQuantize {
+                _engine: Default::default(),
                 value:   24,
                 focused: false
             },
             sync:      TransportSync {
+                _engine: Default::default(),
                 value:   timebase.ppq() as usize * 4,
                 focused: false
             },
             clock:     TransportClock {
+                _engine: Default::default(),
                 frame:   0,
                 pulse:   0,
                 ppq:     0,
@@ -142,7 +147,7 @@ impl TransportToolbar {
         self.timebase.frame_to_usec(self.clock.frame as f64) as usize
     }
 }
-impl Focus<5, Tui> for TransportToolbar {
+impl Focus<5, Tui> for TransportToolbar<Tui> {
     fn focus (&self) -> usize {
         self.focus
     }
@@ -168,7 +173,7 @@ impl Focus<5, Tui> for TransportToolbar {
         ]
     }
 }
-impl Focusable<Tui> for TransportToolbar {
+impl Focusable<Tui> for TransportToolbar<Tui> {
     fn is_focused (&self) -> bool {
         self.focused
     }
@@ -176,16 +181,19 @@ impl Focusable<Tui> for TransportToolbar {
         self.focused = focused
     }
 }
-process!(TransportToolbar |self, _client, scope| {
-    self.update(&scope);
-    Control::Continue
-});
+impl<E: Engine> Process for TransportToolbar<E> {
+    fn process (&mut self, _: &Client, scope: &ProcessScope) -> Control {
+        self.update(&scope);
+        Control::Continue
+    }
+}
 
-pub struct TransportPlayPauseButton {
+pub struct TransportPlayPauseButton<E: Engine> {
+    pub _engine: PhantomData<E>,
     pub value:   Option<TransportState>,
     pub focused: bool
 }
-impl Focusable<Tui> for TransportPlayPauseButton {
+impl Focusable<Tui> for TransportPlayPauseButton<Tui> {
     fn is_focused (&self) -> bool {
         self.focused
     }
@@ -194,11 +202,12 @@ impl Focusable<Tui> for TransportPlayPauseButton {
     }
 }
 
-pub struct TransportBPM {
+pub struct TransportBPM<E: Engine> {
+    pub _engine: PhantomData<E>,
     pub value:   f64,
     pub focused: bool
 }
-impl Focusable<Tui> for TransportBPM {
+impl Focusable<Tui> for TransportBPM<Tui> {
     fn is_focused (&self) -> bool {
         self.focused
     }
@@ -207,11 +216,12 @@ impl Focusable<Tui> for TransportBPM {
     }
 }
 
-pub struct TransportQuantize {
+pub struct TransportQuantize<E: Engine> {
+    pub _engine: PhantomData<E>,
     pub value:   usize,
     pub focused: bool
 }
-impl Focusable<Tui> for TransportQuantize {
+impl Focusable<Tui> for TransportQuantize<Tui> {
     fn is_focused (&self) -> bool {
         self.focused
     }
@@ -220,11 +230,12 @@ impl Focusable<Tui> for TransportQuantize {
     }
 }
 
-pub struct TransportSync {
+pub struct TransportSync<E: Engine> {
+    pub _engine: PhantomData<E>,
     pub value:   usize,
     pub focused: bool
 }
-impl Focusable<Tui> for TransportSync {
+impl Focusable<Tui> for TransportSync<Tui> {
     fn is_focused (&self) -> bool {
         self.focused
     }
@@ -233,14 +244,15 @@ impl Focusable<Tui> for TransportSync {
     }
 }
 
-pub struct TransportClock {
+pub struct TransportClock<E: Engine> {
+    pub _engine: PhantomData<E>,
     pub frame:   usize,
     pub pulse:   usize,
     pub ppq:     usize,
     pub usecs:   usize,
     pub focused: bool,
 }
-impl Focusable<Tui> for TransportClock {
+impl Focusable<Tui> for TransportClock<Tui> {
     fn is_focused (&self) -> bool {
         self.focused
     }
diff --git a/crates/tek_sequencer/src/transport_handle.rs b/crates/tek_sequencer/src/transport_handle.rs
index 03833f3f..dceeb1c3 100644
--- a/crates/tek_sequencer/src/transport_handle.rs
+++ b/crates/tek_sequencer/src/transport_handle.rs
@@ -1,6 +1,6 @@
 use crate::*;
 
-impl Handle<Tui> for TransportToolbar {
+impl Handle<Tui> for TransportToolbar<Tui> {
     fn handle (&mut self, from: &Tui) -> Perhaps<bool> {
         Ok(None)
         //Ok(
@@ -13,13 +13,13 @@ impl Handle<Tui> for TransportToolbar {
     }
 }
 
-impl Handle<Tui> for TransportPlayPauseButton {
+impl Handle<Tui> for TransportPlayPauseButton<Tui> {
     fn handle (&mut self, from: &Tui) -> Perhaps<bool> {
         Ok(None)
     }
 }
 
-impl Handle<Tui> for TransportBPM { 
+impl Handle<Tui> for TransportBPM<Tui> { 
     fn handle (&mut self, from: &Tui) -> Perhaps<bool> {
         //TransportFocus::BPM   => {
             //transport.timebase.bpm.fetch_add(1.0, Ordering::Relaxed);
@@ -31,7 +31,7 @@ impl Handle<Tui> for TransportBPM {
     }
 }
 
-impl Handle<Tui> for TransportQuantize {
+impl Handle<Tui> for TransportQuantize<Tui> {
     fn handle (&mut self, from: &Tui) -> Perhaps<bool> {
         //TransportFocus::Quant => {
             //transport.quant.value = next_note_length(transport.quant)
@@ -43,7 +43,7 @@ impl Handle<Tui> for TransportQuantize {
     }
 }
 
-impl Handle<Tui> for TransportSync {
+impl Handle<Tui> for TransportSync<Tui> {
     fn handle (&mut self, from: &Tui) -> Perhaps<bool> {
         //TransportFocus::Sync  => {
             //transport.sync.value = next_note_length(transport.sync)
@@ -55,7 +55,7 @@ impl Handle<Tui> for TransportSync {
     }
 }
 
-impl Handle<Tui> for TransportClock {
+impl Handle<Tui> for TransportClock<Tui> {
     fn handle (&mut self, from: &Tui) -> Perhaps<bool> {
         //TransportFocus::Sync  => {
             //transport.sync.value = next_note_length(transport.sync)
diff --git a/crates/tek_sequencer/src/transport_view.rs b/crates/tek_sequencer/src/transport_view.rs
index 896481a2..03bee34c 100644
--- a/crates/tek_sequencer/src/transport_view.rs
+++ b/crates/tek_sequencer/src/transport_view.rs
@@ -2,34 +2,26 @@ use crate::*;
 
 const CORNERS: Corners = Corners(NOT_DIM_GREEN);
 
-impl Layout<Tui> for TransportToolbar {
-    fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
-        Ok(Some([area.x(), area.y(), area.w(), 2]))
-    }
-}
-
-impl Render<Tui> for TransportToolbar {
-    fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
+impl Content for TransportToolbar<Tui> {
+    type Engine = Tui;
+    fn content (&self) -> impl Widget<Engine = Tui> {
         Split::right()
             .add_ref(&self.playing)
             .add_ref(&self.bpm)
             .add_ref(&self.quant)
             .add_ref(&self.sync)
             .add_ref(&self.clock)
-            .render(to.with_rect(self.layout(to.area())?.unwrap()))
     }
 }
 
-impl Layout<Tui> for TransportPlayPauseButton {
+impl Widget for TransportPlayPauseButton<Tui> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         area.expect_min(10, 1)?;
         Ok(Some([area.x(), area.y(), 10, 1]))
     }
-}
-
-impl Render<Tui> for TransportPlayPauseButton {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
-        let Self { value, focused } = &self;
+        let Self { value, focused, .. } = &self;
         Layers(&[
             &focused.then_some(CORNERS),
             &Inset::W(1, Styled(match value {
@@ -70,18 +62,16 @@ impl Render<Tui> for TransportPlayPauseButton {
     }
 }
 
-impl Layout<Tui> for TransportBPM {
+impl Widget for TransportBPM<Tui> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         area.expect_min(10, 1)?;
         Ok(Some([area.x(), area.y(), 10, 1]))
     }
-}
-
-impl Render<Tui> for TransportBPM {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let area = to.area();
         let [x, y, ..] = area;
-        let Self { value, focused } = self;
+        let Self { value, focused, .. } = self;
         to.blit(&"BPM", x, y, Some(NOT_DIM))?;
         let bpm = format!("{}.{:03}", value, (value * 1000.0) % 1000.0);
         to.blit(&bpm, x, y + 1, Some(NOT_DIM_BOLD))?;
@@ -96,17 +86,15 @@ impl Render<Tui> for TransportBPM {
     }
 }
 
-impl Layout<Tui> for TransportQuantize {
+impl Widget for TransportQuantize<Tui> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         area.expect_min(10, 1)?;
         Ok(Some([area.x(), area.y(), 10, 1]))
     }
-}
-
-impl Render<Tui> for TransportQuantize {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let [x, y, ..] = to.area();
-        let Self { value, focused } = self;
+        let Self { value, focused, .. } = self;
         to.blit(&"QUANT", x, y, Some(NOT_DIM))?;
         let name = ppq_to_name(*value as usize);
         let width = name.len() as u16;
@@ -121,17 +109,15 @@ impl Render<Tui> for TransportQuantize {
     }
 }
 
-impl Layout<Tui> for TransportSync {
+impl Widget for TransportSync<Tui> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         area.expect_min(10, 1)?;
         Ok(Some([area.x(), area.y(), 10, 1]))
     }
-}
-
-impl Render<Tui> for TransportSync {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let [x, y, ..] = to.area();
-        let Self { value, focused } = self;
+        let Self { value, focused, .. } = self;
         to.blit(&"SYNC", x, y, Some(NOT_DIM))?;
         let name = ppq_to_name(*value as usize);
         let width = name.len() as u16;
@@ -146,17 +132,15 @@ impl Render<Tui> for TransportSync {
     }
 }
 
-impl Layout<Tui> for TransportClock {
+impl Widget for TransportClock<Tui> {
+    type Engine = Tui;
     fn layout (&self, area: [u16;4]) -> Perhaps<[u16;4]> {
         area.expect_min(10, 1)?;
         Ok(Some([area.x(), area.y(), 20, 1]))
     }
-}
-
-impl Render<Tui> for TransportClock {
     fn render (&self, to: &mut Tui) -> Perhaps<[u16;4]> {
         let [x, y, width, _] = to.area();
-        let Self { frame: _frame, pulse, ppq, usecs, focused } = self;
+        let Self { frame: _frame, pulse, ppq, usecs, focused, .. } = self;
         let (beats, pulses)    = if *ppq > 0 { (pulse / ppq, pulse % ppq) } else { (0, 0) };
         let (bars, beats)      = ((beats / 4) + 1, (beats % 4) + 1);
         let (seconds, msecs)   = (usecs / 1000000, usecs / 1000 % 1000);